The present invention relates to a process and an apparatus for shaping a detonation wave, particularly but not exclusively applicable to hollow charges.
Shaped charges and particularly hollow charges are well known and are widely used in means for piercing or cutting e.g. a thick plate. In hollow charges, the explosive which is called the "useful" explosive and which moves the coating of the cavity is frequently initiated by a priming explosive block. If a shield is placed between these two components, a toroidal detonation wave is produced in the useful explosive, which improves the piercing performance levels of the charge.
Throughout the remainder of the present text the term "charging explosive" or "useful explosive" will be used to describe the explosive for moving the coating. The term "priming explosive" designates an explosive mass for transmitting to the useful explosive the detonation wave emitted by a detonator.
The shield makes it necessary for the detonation wave to pass round the latter so that it arrives frontally, in the vicinity of the top thereof, on the conical surface defining the hollowed out part of the charging explosive. It is known that this leads to an increase in the efficiency of the hollow charge.
However, conventional means suffer from the following disadvantage. The shield is almost always made from a compact material, which can be an organic material such as nylon, but other materials are also possible (metals, polymers, ceramics). However, the detonation wave transmitted by the priming explosive produces a shock wave in the shield, which is propagated in the latter at a very high velocity and is then transmitted to the interior of the charging explosive. Due to the very high velocity of the shock wave in the compact shield, the latter arrives at a given point of the charging explosive before the detonation wave from the priming explosive and which has passed round the shield. This disturbs the detonation, which is propagated in a medium which is already compressed by the shock and can even stop the detonation. In less serious cases, the detonation wave has symmetry defects.